JPS6331484B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides at least one organic halogen compound containing, in addition to the photoinitiator, certain organohalogen compounds in order to achieve improved hardness upon irradiation with actinic radiation.
The present invention relates to photopolymerizable compositions containing various photopolymerizable olefinically unsaturated organic compounds. The compositions are used as photopolymerizable coating and recording materials and are particularly suitable as materials for the production of printing plates, photosensitive varnish transfer films and silver-free photopolymer photolithographic films. Photopolymerizable coating materials and recording materials for the abovementioned purposes are known per se, and numerous combinations of compounds for improving the hardness of materials by UV irradiation have already been described in the literature. A frequent drawback of known coating and recording materials that are solid at room temperature is that the rate of polymerization induced by actinic radiation is
Particularly when the toughness or viscosity of the material is high, it decreases markedly at the end of the reaction and, at normal irradiation times, practically complete polymerization or crosslinking of the olefinic unsaturation present is not achieved. In practice, this is therefore useful, especially if the non-irradiated areas are washed out with a solvent after imagewise irradiation or if the surface tack or adhesion value to flat substrates varies depending on the degree of photopolymerization. The seed coating or recording material must be irradiated for a long time. German Patent Application No. 1947194, US Patent
4040923 and 4043887, benzophenone derivatives having a chlorinated or brominated methyl group in the aromatic ring, such as 4-chloromethylbenzo, are used as photoinitiators for photopolymerizable compounds. Phenone, 3,4- or 4,
It is known to use 4'-bis-(chloromethyl)-benzophenone or 4,4'-bis-(bromomethyl)-benzophenone. However, the photosensitivity of this system is still unsatisfactory. A further disadvantage is that the ratio of photoinitiator to activator cannot be varied. German Patent Application No. 2404156, US Patent
No. 3933682, No. 3966573 and Belgian patent 853935
According to each specification, (a) acyloin or aromatic ketone is used as a photoinitiator system, (b) N, P, As, Bi
Alternatively, it is known to use a combination of Sb-containing compounds such as amines, phosphine or arsine and (c) halogenated aliphatic, cycloaliphatic or aromatic hydrocarbons. However, the storage stability of recording materials containing this system is often unsatisfactory. Moreover, basic compounds such as amines
When using (b), it is often not possible to distinguish between the general nature of the illuminated and non-illuminated images due to the discoloration of the commonly added dye indicators. It is an object of the present invention to make it possible, in particular for room temperature solid photopolymerizable compositions comprising photopolymerizable olefinically unsaturated organic compounds, to achieve improved curing with normal irradiation times. , and with regard to the appropriate washout times when washing out the non-irradiated parts with solvents, a more open-ended operation is also possible by applying normal irradiation times, and there are few disadvantages of the known systems. The goal was to find a photoinitiator-activator system with little or no photoinitiator. The inventors have found that the desired improvement is achieved when the photoinitiator system contains as halogenated hydrocarbon a benzole compound having two or more dichloromethyl groups attached to the benzole nucleus. The present invention comprises at least one photopolymerizable olefinically unsaturated organic compound and, as an activated photoinitiator system, (a) at least one aromatic compound that forms radicals that initiate polymerization upon irradiation with actinic radiation; A photopolymerizable composition comprising a group carbonyl compound and (b) a benzole compound having two or more dichloromethyl groups bonded to a benzole nucleus. Preferably, the composition according to the invention additionally contains an indicator dye whose color changes on addition of acid. At least two molecules bound to the benzene nucleus contained in the photoinitiator system activated in the present invention
As a benzole compound having dichloromethyl groups (-CHCl ₂ ), the following formula is used: A compound represented by is used. The substituents ^R1 to ^R6 in this formula may be the same or different, at least two of which are _-CHCl2 , and the remaining groups may be the same or different and are arbitrarily selected,
However, this group behaves inertly towards dichloromethyl groups, does not interfere with photopolymerization and does not show strong absorption in the range of actinic radiation, i.e. an extinction coefficient of 10 is preferably 20 in the range λ = 315-400 nm. It is assumed that it is smaller than [little mole ^-1 cm ^-1 ]. Preferably, the remaining groups include the following. Hydrogen atoms, halogen atoms, especially chlorine atoms,
_C1 ~ _C10 - hydrocarbon residue, halogenated C1 _~
C ₁₀ alkyl group or optionally halogenated
_C1 - _C10 -alkoxy group. Suitable benzole compounds having a dichloromethyl group include bis-
(dichloromethyl)-benzole, e.g. 1,4-
bis(dichloromethyl)-benzole and 2,5
-dichloro-1,4-bis(dichloromethyl)-
I can give you benzol. The amount of dichloromethylbenzole compound added is
Generally, activator per 1 part by weight of photoinitiator (a)
(b) 0.2 to 12 parts by weight, in which case the concentration of the activator is 0.5% or more by weight of the total composition. As the at least one aromatic carbonyl compound (a) which generates polymerization-initiating radicals by actinic radiation, aromatic carbonyl compounds known as photoinitiators, such as aromatic aldehydes and aromatic ketones, are used. In particular, the above-mentioned US patent 3933682
Column 1, line 35 to column 2, line 19 of the issue specification and “Light Sensitive Systems” by Koser, published by G. Wiley, New York, 1965, 158.
Reference is made to the corresponding compounds cited on pages 1 to 193, which can be used as mixtures thereof or in combination with other photoinitiators. In particular, optionally substituted benzophenones such as benzophenones and Michler's ketones, benzoin ethers such as benzoin-isopropyl ether, in the alpha position
Ethers of benzoin substituted by _C1 - _C8 -hydroxyalkyl groups, _C2 - _C8 -alkoxyalkyl groups or _C1 - _C7 -hydrocarbon residues, e.g.
-Hydroxymethylbenzoin-methyl ether, benzyl ketals such as benzyl methyl ketal, anthraquinone and its derivatives, thioxanthone and its derivatives, and benzophenone derivatives such as benzophenone in combination with Michler's ketone are recommended. The individual suitability of a particular photoinitiator (combination) is readily determined by simple manual testing once the teachings of the present invention are known. The material containing at least one photopolymerizable olefinically unsaturated organic compound includes a coating,
The photopolymerizable materials known per se described for the production of printing plates, photoresist materials, photosensitive varnish transfer films, silver-free photopolymerizable films and similar purposes are used. This material contains olefinically unsaturated organic compounds in the form of olefinically unsaturated monomers, prepolymers or polymers having olefinically unsaturated C--C double bonds.
The olefinic unsaturated compound contains at least one terminal CH ₂ =C group, exhibits a boiling point of 100°C or higher at atmospheric pressure, and is capable of producing a polymer through a photoinitiated polymerization reaction. It requires that. Suitable materials include, for example, U.S. Pat.
German Patent Application No. 1622297, German Patent Application No. 1522444, German Patent Application No. 2215090, or Belgian Patent Application No. 560154. In that case, the teachings of the present invention provide materials that are either solid at room temperature before curing (irradiation) or solid at room temperature after about 50% of the photopolymerizable olefinically unsaturated C-C double bonds have reacted. It is particularly advantageous for photopolymerizable materials to be formed, ie for photopolymerizable materials that exhibit high toughness or viscosity at the end of curing, thereby providing low mobility for the reactants. Good compositions contain polymerization products in addition to photopolymerizable monomers as binder components. This organic polymer binder should be generally compatible with the monomers used and, as is obvious to the expert, in the case of imagewise irradiation, the non-irradiated layer of photopolymerizable material. It must be soluble or dispersible in the developing solvent in order to be able to wash out the non-crosslinked parts. Suitable polymerized olefinic saturated or unsaturated binders include linear polyamides and especially alcohol-soluble copolyamides, such as those described in French Patent No. 1,520,856. Cellulose derivatives, especially cellulose derivatives washable with aqueous alkali, vinyl alcohol polymers and polymers and copolymers of vinyl esters of aliphatic monocarboxylic acids having 1 to 4 carbon atoms, such as various degrees of saponification. Polymers and copolymers of vinyl acetate, vinyl pyrrolidone, homopolymers and copolymers of vinyl chloride or styrene, polyurethanes, polyether urethanes, polyester urethanes, polyester resins,
copolymers of acrylic acid and methacrylic acid esters, such as acrylic acid, methacrylic acid, acrylamide and/or hydroxyalkyl acrylate or copolymers of hydroxyalkyl methacrylate and methyl methacrylate, and elastomeric diene polymers and -copolymers, For example, block copolymers from homo- or copolymer blocks of butadiene and/or isoprene and polymer blocks of styrene or α-methylstyrene. Among the low molecular weight compounds having at least one photopolymerizable olefinically unsaturated double bond,
The monomer itself has a photopolymerizable double bond with two or more olefinically unsaturated bonds,
Alternatively, a mixture of this monomer and a monomer having only one photopolymerizable olefinically unsaturated double bond is excellent. The type of monomer used depends broadly on the intended use and the type of polymeric binder used. That is, in the case of mixtures with unsaturated polyester resins, in particular allyl compounds having two or more double bonds, such as dialkyl maleates, allyl acrylates, diallyl phthalates, di- and triallyl esters of trimellitic acid or ethylene glycol bisallyl. carbonates, and di- and polyacrylates and -methacrylates (produced by esterification of diols or polyols with acrylic or methacrylic acid), such as ethylene glycol, diethylene glycol, triethylene glycol, ca.
Polyethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol (2,2-
Preference is given to the di- and triacrylates (or methacrylates) of dimethyl-propanediol), 1,4-butanediol, 1,1,1-trimethylolpropane, glycerin or pentaerythritol. Furthermore, monoacrylates and monomethacrylates of such diols and polyols,
For example, containing ethylene glycol- or di-, tri- or tetraethylene glycol monoacrylate, urethane groups and/or amide groups,
Also suitable are low molecular weight compounds prepared from monomers having two or more olefinically unsaturated bonds, such as aliphatic diols of the type mentioned above, organic diisocyanates and hydroxyalkyl acrylates (or methacrylates). Mention may also be made of acrylic acid, methacrylic acid and their derivatives, such as acrylic (or methacrylic) amide, N-hydroxymethyl acrylic (or methacrylic) amide or acrylates or methacrylates of monoalcohols having 1 to 6 carbon atoms. Mixtures of allyl monomers and di- or polyacrylates are particularly suitable. If mixtures with polyamides are chosen as polymeric binders, in addition to di- and polyacrylates, among the aforementioned monomer types monomers containing double bonds and also amide groups and/or urethane groups are preferred. 1 mole of an aliphatic diol such as a derivative of acrylamide, such as ethylene glycol, and N-
Reaction product with 2 moles of hydroxymethylacrylic (or methacryl)amide, xylylene-bis-
Suitable acrylamides are alkylene-bis-acrylamides having 1 to 8 carbon atoms in the alkylene group. In order to produce aqueous-alkaline developable printing plates using polyvinyl alcohol as the polymeric binder, water-soluble monomers such as hydroxyethyl acrylate (or methacrylate) and molecular weights of about 200 to 500 are used. Suitable are the mono- and diacrylates (or methacrylates) of polyethylene glycol having .
In order to produce photosensitive varnish-coated films (for the production of photoresists) using copolymers of acrylates or methacrylates, such as methyl methacrylate copolymers, as polymeric binders, the following must first be done in connection with polyester resins. Polyacrylates (or methacrylates) are suitable. The proportions in the mixture of monomer and polymeric binder can vary within a wide range, generally between 10 and 55% by weight of the monomer and especially between 25 and 50% by weight of the total amount of the monomer and the polymeric binder. The agent is 45 to 90% by weight, especially 50 to 90% by weight.
It is 75% by weight. The amount of activated photoinitiator system added from photoinitiator (a) and activator (b) in the above ratios is generally 1% to the total weight of the photopolymerizable composition, i.e. the sum of the amounts of all components. -25% by weight, especially 2-20% by weight. The amount of photoinitiator used depends on its extinction coefficient and the thickness of the material layer upon curing, and is usually based on the total amount of the composition.
0.5-10% by weight, especially about 1-5% by weight. The amount of activator (b) is at least 0.5%, especially about 1 to 12% by weight of the total composition, and is influenced by the desired curability of the material layer. Often in the same photoinitiator-activator formulation, when moving to a thicker material layer, the concentration of the photoinitiator is increased in order to avoid a stronger absorption of UV radiation in this thicker material layer. It is particularly advantageous to keep the concentration of the activator unchanged, even if it is low. The compositions of the invention contain photopolymerizable compounds, polymeric binders, photoinitiators and activators, as well as conventional additives in conventional amounts, such as inorganic or organic pigments or dyes, inorganic or organic fillers, polymerization inhibitors such as hydroquinone or tertiary-butylhydroquinone, antiskinning agents such as paraffin, flow aids such as silicone oils, matting agents or lubricants such as waxes, organic solvents such as alcohols, hydrocarbons or ketones. can. The photopolymerizable composition of the invention preferably uses an indicator dye which changes color when an acid is added, such as 3'-phenyl-7-diethylamino-
2,2'-spirodi-(2H-1-benzopyrone),
Bromocresol green or methyl orange is generally contained in an amount of 0.05 to 2% by weight. Dyes without amino groups, which form ammonium salts with acids and darken the color, are highly suitable. To initiate photopolymerization, light with a wavelength of 2300-4500 Å, especially light with an emission maximum of 3000-4200 Å, is used. Suitable irradiation sources are mercury high-pressure lamps, superactinic phosphor tubes, xenon impulse lamps, metal iodide feed lamps and carbon arc lamps. The compositions of the present invention can be applied to coatings, UV-curable printing inks and printing pastes, photopolymer printing plates, photoresists, photosensitive varnish transfer films and silver-free photopolymer photographs by means known per se. Processed into film for plate making. The special benzene compound (b) with dichloromethyl group contained in the composition of the invention has a strong activating effect and at the same time has very good affinity for many binders and monomers. and is surprisingly highly chemically inert compared to, for example, the structurally similar benzal chloride.
It was completely unpredictable. By adding water and silver nitrate to a methanol solution of the dichloromethyl group-containing benzole compound (b), precipitation of silver chloride does not occur at all. Since activator (b) shows little light absorption above 310 nm, this also does not interfere with the absorption of photoinitiators or dyes. Parts and percentages in the following Examples and Comparative Examples are by weight unless otherwise specified, and parts are by volume.
There is a relationship between Kg vs. Comparative Example 1 Adipic acid, hexamethylene diamine, 4,
100 parts of an alcohol-soluble copolyamide prepared by copolycondensation of 4'-diaminodicyclohexylmethane and ε-caprolactam, and m-
15 parts of xylylene bisacrylamide, 10 parts of triethylene glycol diacrylate, 17 parts of N-methylol methacryl methyl ether, 1 part of benzoin methyl ether, and 0.1 part of Cer() salt of N-nitrosocyclohexylhydroxylamine were added to 300 parts of methanol for 60 parts. Dissolve at °C. This viscous solution is dry-rolled in a roll device at a temperature of 60-80°C. The sheet treated with this roll is shredded and compressed using a press at 170°C under a pressure of 200 kg/cm ² to form a colorless and transparent plate with a thickness of 0.8 mm. This plate is adhered onto an aluminum plate using a double-sided adhesive film. The thus produced photopolymerizable book printing plates were subjected to electrophotographic test negatives (48 lines/cm) in a commonly available commercial printing plate-irradiation apparatus equipped with eight low-pressure fluorescent tubes of 20 W each. Irradiate in hours. After 24 hours of storage, the non-irradiated parts of the printing plates were treated with a propanol-ethanol-water mixture (7:2:1).
The washing is carried out in a washing device, which consists of a pump and a number of injection nozzles, which sprays the solvent at a pressure of 3 atmospheres onto the plate to be washed. After 10 minutes, the washing process is interrupted, the plates are washed with fresh propanol and the adhering solvent is removed with compressed air. The irradiation times required to completely form a 3% screen tone value in relief are shown in Table 1. Example 1 The procedure is as in Comparative Example 1, except that 5 parts of 1,4-bis(dichloromethyl)-benzole are further added to the viscous liquid for the production of book printing plates. Table 1 shows the results of the irradiation test conducted in the same manner as in Comparative Example 1.

[Table] = Good comparative example 2 60 parts of copolymer of 70% methyl methacrylate, 5% 2-ethylhexyl acrylate, 5% styrene and 20% methacrylic acid (azoisobutyronitrile in acetic ester as polymerization initiator) (produced by solution polymerization), 25 parts of pentaerythritol-tetraacrylate, hexanediol-
5 parts of 1,6 dimethacrylate, 2 parts of Michler's ketone, 2.5 parts of benzophenone, 0.2 parts of hydroquinone monomethyl ether, and Disperse blue.
A solution of 0.5 part of 148 in 300 parts of acetic acid was divided into two equal parts (A
and B). Part A of the solution was deposited on a commercially available anodized aluminum plate after drying.
Apply by dipping so that a layer of 0.006 mm remains. Next, a polyvinyl alcohol layer with a thickness of 6 μm is formed from the aqueous solution by immersion in the same manner, and then dried. The offset printing plate thus obtained is illuminated over its entire surface using a 14-step gray scale for electrophotography. This gray scale has a minimum optical density of 0.4 at 370 nm, with each step decreasing in optical density by 20% of the previous step. After a sufficient irradiation time of 65 seconds (when the photosensitive varnish changes color from dark blue to light blue) and development with a phosphate buffer solution having a pH of 10, the printing plate is well printed on a small offset printing press. The printing performance was shown. Furthermore, the formation of stages is evaluated at specific irradiation times of 1 to 10 minutes. Example 2 In part B of the solution described in Comparative Example 2, 2.5 parts of 2,5-dichloro-1,4-bis(dichloromethyl)-benzole are dissolved. Other processing and testing are
The same procedure as in Comparative Example 2 is carried out. The printing plates irradiated and developed with an exposure time of 50 seconds showed good printing performance, similar to the plate of Comparative Example 2 (65 seconds exposure time). Evaluation of step formation at irradiation times of 1 to 10 minutes shows that when compared with the corresponding test of Comparative Example 2, the board of Example 2 formed 2 to 3 more steps than the board of Comparative Example 2, respectively, at the same irradiation time. It was known that it would happen. Examples 3 and 4 54 parts of a copolymer from 97% methyl methacrylate and 3% acrylamide (prepared by polymerization with benzoyl peroxide in acetate as initiator, as a 1% solution in acetate) 13, 1932, p. 60), 38.5 parts of 1,1,1-trimethylolpropane triacrylate, 1.5 parts of divinylethylene urea, 2.5 parts of benzophenone, N-
From 0.025 parts of nitrosodiphenylamine, 0.011 parts of crystal violet, 0.3 parts of 3'-phenyl-7-diethylamino-2,2'-spirodi-(2H-1-benzopyrone), adipic acid and 1,2-propylene glycol. Polyester (7pa・
sec/20 DEG C.), 0.3 parts of a commonly available silicone oil and 1.5 parts of 1,4-bis(dichloromethyl)-benzole are dissolved in 140 parts of acetic ester. The solution is passed through a pressure vessel with a pore size of 1 μm and cast under hot air onto a 0.023 mm thick polyester film in such a way that a layer of 0.048 mm of photosensitive varnish remains. This photosensitive varnish film is covered with a 30 μm thick polyethylene film. This three-layer film is cut into 50 cm width pieces, rolled up onto paperboard cores, and stored as rolls in a dark place. Prior to use as a dry-stick photosensitive varnish, the polyethylene-coated film is peeled off in a common commercial laminating machine and the varnish is applied onto a pre-brushed copper-platinated epoxy resin-fiberglass board. At a speed of 1 m/min and at 110°C. Chamfer and cut this board to make it even, and process it as shown below. Example 3 The board is irradiated with ultraviolet light for 1 minute through a photographic negative original of the electrical wiring image. The illuminated image area changes color from blue-violet to dark blue, producing excellent contrast. The polyester film is then peeled off and the non-irradiated image area is washed out with 1,1,1-trichloroethane. Then, it is corroded using Baume's 44°C iron chloride solution, washed with water, and dried. By washing this plate with acetone for 1 minute, the irradiated photosensitive varnish is washed out and a conductive plate is obtained. Example 4 The board is irradiated with ultraviolet light for 1 minute through a positive original of the electrical wiring image. Next, the polyester film is peeled off and the non-irradiated image area is washed out.
Copper is deposited sequentially by electroplating on exposed copper surfaces.
Deposit 0.035mm, nickel 0.005mm and gold 0.002mm. The remaining photosensitive varnish is then washed away by methylene chloride washing, and finally the exposed copper is corroded using an ammoniacal copper nitrate solution, resulting in a conductive printed wiring board with excellent sharpness of the conductive circuits. Comparative Examples 3 and 4 The procedure is as in Examples 3 and 4, but the addition of 1,4-bis-(dichloromethyl)-benzole is omitted during the preparation of the varnish solution. Example 3
In order to obtain results comparable to and 4, the required irradiation time of 1 minute must be extended to 1 minute and 35 seconds. Furthermore, no discoloration to dark blue is observed after irradiation. Examples 5 and 6 and Comparative Examples 5 to 11 53 parts of the copolymer described in Example 3, 20 parts of trimethylolpropane triacrylate, reaction product of 1,4-butanediol diglyside ester and an equivalent amount of acrylic acid 10 parts, triethylene glycol diacrylate 6 parts, divinylpropylene urea
0.5 parts, 2.5 parts of benzophenone, Michler's ketone
0.4 parts, 0.05 parts of 2,6-ditertiary-butyl-4-methylphenol, 3.5 parts of tribenzyl phosphate, and 3'-phenyl-7-diethylamino-2,
A solution of 0.3 parts of 2'-spirodi-(2H-1-benzopyrone) in 200 parts of acetic acid ester is prepared. In each identical solution of this type, the chlorine compounds listed in Table 2 are mixed in the amounts listed therein. The 28 different solutions thus produced are processed into photosensitive varnish films by operating as described in Examples 3 and 4. This is then laminated onto a copper-plated epoxy resin-fiberglass board and irradiated with ultraviolet light through a photographic negative of a wiring motif with a conductive circuit 0.1 mm wide. The irradiation time is only 45 seconds instead of the 1 minute required for processing.
After storage for 1 hour and peeling off the polyester film, it is developed using 1,1,1-trichloroethane.
In each case, a mechanically driven plush brush is continuously moved in a circular motion over the wiring image. The minimum development time required is 10 in all examples.
~15 seconds. For all samples, the maximum permissible time (after which the illuminated image part of the varnish layer on the copper surface also dissolves) is determined. The results are shown in Table 2. This clearly shows the effect of the compounds according to the invention on photopolymerization. Although the difference is small in the irradiation time of 1 minute, the effect is still measurable even with 10 times excessive irradiation (600 seconds).

[Table] Talin Example 7 49 parts of reaction product from 1 mole of hexamethylene diisocyanate and 2 moles of hydroxypropyl acrylate, reaction product from 1 mole of toluylene diisocyanate and 2 moles of hydroxypropyl acrylate, 8 parts of pentaerythritol-tetraacrylate p,p-bis-(diethylamino)
- 3 parts of benzophenone, 3 parts of p-dimethylaminobenzaldehyde, 4 parts of benzophenone, 3 parts of 4-phenylamino-azobenzole and 2,5-
A photocurable printing ink binder is prepared from 10 parts of dichloro-1,4-bis(dichloromethyl)-benzole. Using a refurbished book printing machine, this binder was used to print five times each on a copper-plated epoxy resin board.
During the printing process, each 1.5 μm ink layer was dried by irradiation for 0.6 seconds with a 1000 Watt mercury high-pressure lamp. As the printing plate, a commonly available commercially available polyamide-based photosensitive polymer convex printing plate was used, and an image of electrical wiring was printed as a motif. After 7.5 μm of printing ink was applied on the board,
Let dry for 0.5 hours, then remove the exposed copper surface.
Corroded using Baume 44 degree iron chloride () aqueous solution. The obtained printed wiring board showed excellent edge sharpness even in minute contour lines and extremely good image dimensional stability even after 1000 copies were printed. The difference from the original did not exceed 2 μm. In contrast, for printed wiring boards manufactured by screen printing, deviations of up to 25 μm were typically measured for the same number of prints. Comparative Example 12 Proceed as in Example 7, but using the same amount of 1,4-bis-(trichloromethyl)-benzole instead of 2,5-dichloro-1,4-bis(dichloromethyl)-benzole. Manufactures book printing plates. This can likewise be used by letterpress printing methods for printing printed circuits.
However, each print had to be exposed for 1.1 seconds. Example 8 The solution according to Example 2 is applied as a coating onto a woven mesh substrate in a layer 20 μm thick. After image-wise irradiation with actinic radiation and development in an aqueous-alkaline solution, the photopolymerized image areas serve as an excellent mask for screen printing.

Claims (1)

Claims: 1 at least one photopolymerizable olefinically unsaturated organic compound and as an activated photoinitiator system: (a) at least one photopolymerizable olefinically unsaturated organic compound which forms radicals that initiate polymerization upon irradiation with actinic radiation; 1. A photopolymerizable composition comprising: (b) a benzole compound having two or more dichloromethyl groups bonded to a benzole nucleus; 2. The photopolymerizable composition according to claim 1, which contains bis-(dichloromethyl)-benzole as the halogenated hydrocarbon (b). 3 As the halogenated hydrocarbon (b), 2,5-dichloromethyl-1,4-bis(dichloromethyl)-
Photopolymerizable composition according to claim 1, characterized in that it contains benzole. 4 Benzole compound with dichloromethyl group
The content of (b) is 0.5% by weight or more based on the total amount of the composition, and the compound (b) is contained in an amount of 0.2 to 12 parts by weight per 1 part by weight of the aromatic carbonyl compound (a). A photopolymerizable composition according to any one of claims 1 to 3. 5. The photopolymerizable composition according to any one of claims 1 to 4, which contains benzophenone or a benzophenone having a substituent as the aromatic carbonyl compound (a). 6. A photopolymerizable composition according to any one of claims 1 to 5, characterized in that it contains an indicator dye whose color changes upon addition of an acid.